The phrase "Why Does My Heart Feel So Bad?" is best known as the title of a song by American musician Moby, released in 1999 on his album Play. The song originally was written in 1992 and later reworked into a slower, more mournful and romantic piece. It is notable for its gospel choir samples and expresses themes of emotional pain, depression, and heartache. The lyrics repeatedly ask this question, reflecting feelings of sadness and soul-searching connected to depression and romantic sorrow. Moby was encouraged by his manager to include it on the album, leading to international success, especially in German- speaking countries and the UK.

If you are asking about the meaning of the phrase in a literal or medical sense—as in actual heart pain or emotional distress—it could be linked to emotional heartache or depression, or in a physical context, to conditions like chest pain caused by heart issues. Heart pain can come from many causes such as angina, heart attack, or emotional stress, which metaphorically might relate to feeling "so bad" in the heart area.

Therefore, "Why does my heart feel so bad?" is both a melancholic expression in the context of the song and can metaphorically relate to emotional suffering, depression, or heartbreak. Physically, chest or heart pain should always be taken seriously and examined by a healthcare professional. For a deeper understanding tailored to your context, whether it's the song's meaning or medical reasons behind heart pain, please specify.